Which of the following most accurately describes changes in autonomic control of heart rate during incremental exercise (from rest to VO2 max)?- PNS outflow is followed by SNS withdrawal- PNS withdrawal is followed by SNS outflow – PNS and SNS outflow- PNS and SNS withdrawal
PNS withdrawal is followed by SNS outflow
The most accurate description of changes in autonomic control of heart rate during incremental exercise, from rest to VO2 max, is PNS withdrawal followed by SNS outflow.
Initially, during rest, the parasympathetic nervous system (PNS) dominates, resulting in decreased heart rate and cardiac output. As exercise intensity increases, there is a gradual reduction in PNS activity, leading to the withdrawal of PNS outflow.
Simultaneously, there is a gradual increase in the sympathetic nervous system (SNS) activity, leading to the outflow of SNS. This increase in SNS activity causes an increase in heart rate, cardiac output, and blood pressure, which are necessary for meeting the metabolic demands of exercise.
At VO2 max, the maximum amount of oxygen the body can uptake, the SNS activity will eventually plateau and level off, while the PNS activity continues to be suppressed. The balance between PNS and SNS is essential in regulating heart rate and cardiac output during exercise.
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